Nuclear medicine (NM) imaging systems, such as Single Photon Emission Computed Tomography (SPECT) imaging systems, use one or more image detectors to acquire image data, such as gamma ray or photon image data. The image detectors may be gamma cameras that acquire two-dimensional views of three-dimensional distributions of radionuclides (from an injected radioisotope) from a patient being imaged.
In SPECT imaging systems, collimators may be placed in front of a scintillation crystal or solid state detector to focus the field of view (FOV) of the detectors. The collimators allow gamma rays aligned with the holes of the collimators to pass through to the detector. These detectors need to be calibrated, including during manufacture and periodically after installation at a clinical site, to ensure proper imaging operation. For example, the detectors are calibrated to provide a uniform energy and sensitivity response across the detector units or output channels.
However, the sensitivity of a SPECT detector may vary based on the type of collimator as well as the type of radioisotope administered to the patient. Such variability in sensitivity limits the accuracy of quantitative measurements with SPECT imaging. To increase precision of quantitative measurements, the sensitivity of a detector may be calibrated for a specific combination of a collimator and radioisotope to be used in a clinical study. However, such calibrations are time-consuming, and require that the imaging system operator has access to the appropriate phantom for a certain radioisotope in addition to knowledge of the different calibration processes for different collimators and radioisotopes.